Lighting the Pilot Light Step by Step

To light an A.O. Smith water heater pilot light, turn the gas control knob to the "Pilot" position, hold down the ignition button while bringing a long lighter or lit match to the pilot burner opening, and keep the button pressed for 30 to 60 seconds after the flame appears. Once the pilot stays lit on its own, turn the knob to "On" and listen for the main burner to ignite within a few seconds.

The pilot light is a small flame that ignites the main heating element. If it goes out, your water heater stops producing hot water. Most A.O. Smith models use a manual ignition system, meaning you light it by hand rather than pushing an electronic starter button. The whole process takes about two minutes and requires no tools.

Key Takeaways

  • Turn the gas control knob to "Pilot" before attempting to light the flame, or gas will flow to the main burner instead.
  • Hold the ignition button down continuously while lighting and for 30 to 60 seconds after the flame appears so the thermocouple can heat up.
  • Use a long lighter or long match to reach the pilot burner opening safely without burning your hand.
  • If the pilot light goes out repeatedly after you light it, the thermocouple may be failing and the unit may need service.

Locate the Pilot Burner and Gas Control Knob

Open the access panel at the bottom front of your A.O. Smith water heater. You will see a small metal tube pointing downward—this is the pilot burner. Just above or beside it is the gas control knob, usually labeled with three positions: "Pilot," "On," and "Off." Some models also have a red ignition button next to the knob.

The pilot burner opening is small, roughly the size of a pencil tip. The gas control knob is the most important part of this process because it determines where gas flows. If you skip the "Pilot" step and turn directly to "On," gas will flood the main burner chamber instead, and you will not be able to light the small pilot flame.

Turn the Knob to Pilot and Press the Ignition Button

Rotate the gas control knob clockwise until it stops at the "Pilot" position. Then press and hold the red ignition button (or the button on the knob itself, depending on your model). You should hear a faint clicking sound—this is the spark igniter attempting to light the pilot. Keep the button pressed while you bring your lighter or match to the pilot burner opening.

Do not release the button yet. The clicking may stop after a few seconds, but that is normal. The ignition button's job is to create the spark; your lighter or match provides the actual flame. Hold both the button and the flame steady for a few seconds until you see the pilot light catch.

Light the Pilot Flame and Hold the Button

Bring the tip of a long lighter or a lit long match to the pilot burner opening while still holding down the ignition button. You should see a small blue flame appear within a few seconds. Once the flame is visible, keep the ignition button pressed for another 30 to 60 seconds. This allows the thermocouple—a heat-sensing device near the pilot flame—to warm up enough to signal the gas valve to stay open.

If you release the button too soon, the pilot light will go out when ready because the thermocouple has not reached the right temperature yet. If you are unsure whether 30 seconds have passed, count slowly to 60 to be safe. The extra time costs nothing and prevents the frustration of having to start over.

Release the Button and Turn the Knob to On

After 30 to 60 seconds, slowly release the ignition button while watching the pilot flame. If the flame stays lit, you have succeeded. Now turn the gas control knob from "Pilot" to "On." Within a few seconds, you should hear a whooshing sound as the main burner ignites. The larger flame in the main chamber will be blue with perhaps some yellow at the tip—this is normal.

If the pilot light goes out when you release the button, wait a minute for the thermocouple to cool, then repeat the process. Sometimes it takes two or three attempts, especially if the thermocouple is old or slightly dirty. If the pilot light consistently goes out after you turn the knob to "On," the thermocouple may need replacement.

Confirm the Main Burner Is Lit and Close the Panel

Look through the access panel opening and confirm that the main burner flame is burning steadily. The flame should be mostly blue. If it is mostly yellow or orange, the burner may need cleaning, but the water heater will still heat water. Close the access panel and wait 10 to 15 minutes. Feel the side of the tank—it should become warm to the touch as the burner heats the water inside.

If you do not feel heat building up after 15 minutes, or if the main burner flame goes out, turn the gas control knob back to "Off" and wait before trying again. Repeated failures usually point to a thermocouple problem or a gas supply issue, both of which require professional service.

Common Mistakes to Avoid

The most common error is turning the knob directly to "On" without stopping at "Pilot" first. This sends gas to the main burner, not the pilot, and you will not be able to light a small flame. Always rotate to "Pilot" and hear or feel it click into place before lighting.

Another mistake is releasing the ignition button too quickly. If you let go after only 10 or 15 seconds, the thermocouple will not be hot enough to keep the gas valve open, and the pilot will die as soon as you release the button. Count to at least 30 before letting go, and do not be afraid to count to 60 if you are uncertain.

A third error is using a short lighter or short match. The pilot burner opening is recessed inside the access panel, and a short flame will not reach it. A long lighter designed for candles or a long fireplace match works best. Keep your hand and arm as far from the flame as the lighter or match length allows.

Frequently Asked Questions

What if I cannot get the pilot light to stay on?

If the pilot light goes out when ready after you release the button, the thermocouple is likely too cool or faulty. Wait one minute and try again, holding the button for a full 60 seconds this time. If it still goes out, the thermocouple may need replacement, which requires a service technician. Do not attempt to replace it yourself.

Is it safe to light the pilot by hand?

Yes, lighting the pilot by hand is the standard method for A.O. Smith water heaters and is safe when you use a long lighter or match and keep your hand clear of the flame. The pilot burner is designed to be lit this way. Always may support the gas control knob is set to "Pilot" before you begin.

How long should the main burner flame be?

The main burner flame should be 4 to 6 inches tall and mostly blue. A small amount of yellow at the tip is normal and does not indicate a problem. If the flame is very short, very tall, or mostly yellow, the burner may need cleaning, but the water heater will still function.

What does it mean if the pilot light keeps going out?

A pilot light that repeatedly goes out after you turn the knob to "On" usually means the thermocouple is failing or the gas supply is unstable. It can also mean the pilot burner opening is clogged with dust or debris. A service technician can diagnose and fix the problem.

Can I light the pilot if I smell gas?

If you smell gas but do not see a leak, turn the gas control knob to "Off" when ready and open windows to ventilate the area. Do not light anything. Wait 15 minutes, then try again. If you smell gas a second time, turn the knob to "Off" and contact a service technician. A strong gas smell may indicate a leak or a problem with the gas valve.